A mechanistic study of stratified patina evolution on Sn-bronze in chloride-rich atmospheres. (15th April 2020)

• Record Type: Journal Article
• Authors: Chang, Tingru; Maltseva, Alina; Volovitch, Polina; Odnevall Wallinder, Inger; Leygraf, Christofer
• Is Part Of: Corrosion science. Volume 166(2020)
• Publication Date: 2020-04-15
• Subjects: Bronze -- Copper -- Tin -- AES -- Raman spectroscopy -- Atmospheric corrosion; Corrosion and anti-corrosives -- Periodicals; 620.11223
• DOI: 10.1016/j.corsci.2020.108477
• Languages: English
• ISSNs: 0010-938X

Abstract

Graphical abstract: Highlights: Patina stratification and flaking on Sn-bronze in Cl-rich atmospheric environments. Patina contains alternating Cu2 O and Cu2 (OH)3 Cl layers intercalated with Sn-oxides. Role of Cl and Sn in patina stratification is elucidated. Stratification is explained via redox reactions of soluble Sn-Cl and Cu-Cl complexes. Patina flaking is explained by molar volume changes during chemical transformation. Abstract: The complex stratified patina formed on Sn-bronze in chloride-rich atmospheres has been explored through long-term field exposures and short-term laboratory investigations using a multi-analytical approach. The stratified patina is composed of Cu2 O- and Cu2 (OH)3 Cl-rich sublayers intercalated by Sn-oxides, mainly SnO2 . The stratification is triggered by events of high chloride deposition, resulting in repeated dissolution and solidification of sublayers, whereby redox reactions between the intermediate products of Sn- and Cu-chlorides play a crucial role. Sn-induced patina stratification is a major reason for enhanced patina flaking on Sn-bronze and its accelerated corrosion rate compared to Cu metal in marine environments.